It is known that, to obtain photographs covering a field even slightly larger than normal, special lenses such as wide-angle lenses are usually used. Fish-eye lenses are sometimes used to cover wider fields, but these cause considerable distortion of the image. However, they obtain photographs covering very extensive fields, up to 180.degree. and even beyond, the so-called panoramic shots, using special cameras which are often very complicated and expensive. Furthermore, these cameras can be used only for the purpose for which they were constructed, and most are of the type described in Canadian Pat. No. 30143 of 1888. Other types of cameras provide various types of systems, all very complex.
A more convenient and particularly attractive solution is described in Pat. No. 1008 filed in Monaco on Aug. 29, 1972, which uses in practice the same principle as the Canadian patent cited above. However, it provides for the use of an ordinary camera attached to a rotating support in which a motor rotates the rotating support itself and at the same time, by means of an appropriate transmission, it also rotates the film rewind spool. As in the Canadian patent, the film's exposure surface is limited by a small vertical slit in a special plate which is inserted into the camera just in front of the sensitive surface of the film itself. However, this solution presents a number of disadvantages. First, the plate with a slit must be put into the camera, and this is impractical and inconvenient because each camera has its own internal structure, which means that an appropriate plate must be used for each type of camera. In addition, when the plate with a slit is put in place, the camera can be used only for panoramic shots. An additional disadvantage of this solution is that, while the shot is being made, the film transfer rate progressively increases because, while the rotation rate of the rewind spool is constant, the diameter of the rewound film increases progressively as the film accumulates on the spool, and this obviously causes substantial variations in the size of the image obtained which, particularly in shots covering very wide fields, are quite noticeable.